s1_read_last_two_bytes_of_a_mbr_backup_file() {
    local file_path=$1
    local last_bytes=$(tail -c 2 "$file_path" | od -A n -t x1 | tr -d ' \n')
    if [ "$last_bytes" = "55aa" ];then
        echo "YES"
    else
        echo "NO"
    fi
}

s2_read_mbr_partition_table_info() {
    for i in {0..3}; do
        offset=$((446 + i * 16))
        start_sector=$(dd if="$1" bs=1 skip=$((offset + 8)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n')
        if ! [[ $start_sector =~ ^[0-9]+$ ]];then
            continue
        fi
        if [ "$start_sector" -eq 0 ];then
            continue
        fi
        size_sector=$(dd if="$1" bs=1 skip=$((offset + 12)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n')
        end_sector=$((start_sector + size_sector - 1))
        echo "$start_sector $end_sector"
    done
}

s3_parse_partition_info(){
    fdisk_output=$(cat)
    disk_size_bytes=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $5}')
    disk_size_sectors=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $7}')
    physical_sector_size=$(echo "$fdisk_output" | grep "Sector size" | awk '{print $4}')
    first_partition_start_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $3}')
    first_partition_end_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $4}')
    first_partition_type=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $8}')
    echo "disk size in bytes:$disk_size_bytes"
    echo "disk size in sectors:$disk_size_sectors"
    echo "physical sector size in bytes:$physical_sector_size"
    echo "first partition start sector id:$first_partition_start_sector"
    echo "first partition end sector id:$first_partition_end_sector"
    echo "first partition type:$first_partition_type"
}

s4_run_passwd_as_plain_user_and_get_status() {
    oversleeping_path=$(which oversleeping)
    chown root "$oversleeping_path"
    chmod 4755 "$oversleeping_path"
    oversleeping &
    ps -o uid,euid,ruid -C oversleeping | awk 'NR>1 {print $1","$2","$3}'
}

s5_add_a_scheduled_task() {
    touch $HOME/test_crontab;
    echo "*/5 * * * * date +\%Y\%m\%d_\%H\%M\%S >> $HOME/test_crontab" | crontab -
}

